Beater bar with dissimilar edges

ABSTRACT

A rotatable beater bar, used for fibrillating film, comprises dissimilar serrated edges mounted thereon for improving fibrillating efficiency.

United States Patent [151 3,650,446 Samluk 51 Mar. 21, 1972 [54] BEATER BAR WITH DISSIMILAR [56] References Clited EDGES UNITED STATES PATENTS [72] Invent Samluk Newark 2,266,958 12/1941 Corbin .33/300 x [73] Assignee: Hercules Incorporated, Wilmington, Del. 3,565,308 2/1971 Slack ..225/97 [22] Filed: 1970 Primary Examiner-Frank T. Yost [2 pp No 0 2 Attorney-John W. Whitson [57] ABSTRACT 2? 'g g2g6g3 A rotatable beater bar, used for fibrillating film, comprises dis. gzi 678 596 similar serrated edges mounted thereon for improving fibril.

83/660; 93/58.2; 28/DIG. 1; 264/DIG. 8

lating efficiency.

5 Claims, 5 Drawing Figures PATENTEDHARZI I972 3,550, 45

SHEET 1 BF 2 v f r x 24 SEE ENLARGED 1 26 30 FIGURE 3 FIG. I

38 4O 38 4O 38 4O 38 STANLEY D. SAMLUK INVENTOR BY $4M 0 L94 AT TOHNE'Y PATENTEUHARZ] I972 3,550,445

SHEEI 2 0F 2 FIG. 5

STANLEY D. SAM LUK INVENTOR ATTORNEY This invention is an improvement on the type of beater bar 4 disclosed in US. Pat. Nos. 3,494,522 and 3,495,752 which has identical serrated edges.

It is an object of this invention to provide a beater bar with dissimilar edges which when used in a film fibrillating system effects increased efficiency and other desirable results.

Other objects of the invention will become apparent from the following description and drawing wherein:

FIG. 1 is a schematic view of a fibrillating system embodying the present invention;

FIG. 2 is a partial view in section of a serrated edge and striated film;

FIG. 3 is an enlarged view of the encircled portion of FIG. 1;

FIG. 4 is a view taken along section line 4-4 of FIG. 1; and

FIG. 5 is a modification of the embodiment of the beater bar shown in FIG. 1.

Referring to FIGS. I-3, a striated ribbon is fed between a pair of feed rolls l2 and a pair of draw rolls 14. The space between the feed rolls 12 and draw rolls 14 defines a fibrillation zone and the rolls 12 and 14 are driven at relative speeds to maintain the section 16 of ribbon 10 in the fibrillation zone under tension. The tensioned section 16 of the film is engaged by a beater bar 18 which comprises six serrated edges 20, 21, 22, 23, 24, and removably and adjustably secured to a base member 26 at equally spaced circumferential positions. Each serrated edge comprises teeth 27 and valleys 28 separating the teeth an equal distance from each other. The serrated edges 20, 22, and 24 are pitched to the right and the serrated edges 21, 23, and 25 are pitched to the left. The angle of pitch for edges 20, 22, and 24 is the same as the angle of pitch for edges 21, 23, and 25. The beater bar 18 is journaled for rotation about its axis by means of a pair oftrunnions 30, 31 extending from each end thereof, which extend into a pair of spaced supports 32 located at each end of the beater bar 18. Rotation of the beater bar 18 is imparted by any well known means as for example by a belt 34 entrained about a pulley 36 secured to the trunnion 31. The beater bar is arranged so that its rotational axis is parallel to the pinch lines of the feed and draw rolls and the edges 20, 21, 22, 23, 24, and 25 thereof engage the film on a line which is outside of a plane passing through the pinch lines whereby upon rotation of the beater bar and upon engagement of the edges with the film, the film will be fibrillated.

The film 10 comprises a thin strip of thermoplastic material such as polypropylene, and, as illustratedin FIG. 2 is striated, or in other words, is provided with a series of substantially uniformly spaced parallel ribs 38 or striations running longitudinally thereof and interconnected by webs 40 of reduced thickness. The film 10 is unaxially oriented in the direction parallel to the striations whereby the film is much stronger in a longitudinal direction than in a transverse direction of the film. In fact the transverse strength of each web is usually such that very little transverse force is required to tear or break the web and separate the striations.

The teeth 26 are rounded at the tip thereof and taper outwardly towards the valley. Fibrillation occurs when the teeth engage a web and due to the tension on the film portion 16, the striations or ribs 38 are forced down against a tooth creating a wedging action forcing the striations 38 apart.

As pointed out in U.S. Pat. Nos. 3,494,522 and 3,495,752, the type of pattern of fibrillation will depend upon the speed of rotation ofthe beater bar, the speed of the film, the angle of the helix path described by the teeth, the spacing of the teeth, the spacing ofthe striations and the strength of the webs.

The serrated edges 20, 22, and 24 are made by placing threads on a bar stock in a helical pattern pitched to the right and then cutting segments from the bar with each segment being a serrated edge. The serrated edges 21, 23, and 25 are made in the same fashion only they are taken from a bar that is threaded in a helical pattern pitched to the left. Each serrated edge is provided with a pair of flanges 42, 44 extending laterally on each side thereof and which slidingly fit in grooves 46 of the beater bar base member 26. A plura ity of axially extending slots 48 are provided in each flange and bolts 50 pass through the slots and secure the edge member to the beater bar base member 26. The provision ofslots allows axial adjustmentof each edge member relative to the beater bar base member 26 which feature does not form a part of this invention and is the subject matter of copending U.S. application Ser. No. 60,681 of David B. Jackson, filed Aug. 3, 1970 concurrently herewith (common assignee).

The edges 20, 22, and 24 are pitched in the opposite direction to edges 21, 23, and 25 in order to impart a more emphatic lateral shifting ofthe film than effected by the beater bar 4 described in U.S. Pat. Nos. 3,494,522 and 3,495,752. All of the edges of beater bar 4 shift the film in the same direction and upon disengagement of the film with each edge, the film portion which was in engagement with that edge laterally snaps back in the opposite direction to align with the rest of the film. With this type of beater bar, one serrated edge must disengage the film prior to the next serrated edge engaging the film or the film will move laterally off of the beater bar since it will be continually moved in one direction. With alternating edges being pitched in opposite directions, each edge biases the film in opposite directions enabling greater lateral reciprocal shifting thus creating greater transverse or lateral stresses on the webs 40 of the film for separating the striations 38. Furthermore, more than one edge can engage the film simultaneously permitting the edges to be spaced closer together increasing the number of edges striking the film per revolution of the beater bar. Thus, it can be seen that this construction effects greater fibrillation control thereby increasing fibrillation efficiency.

The beater bar 18 is also useful in a fibrillation system where two opposed intermeshing beater bars are used as described in copending U.S. application Ser. No. 60, 444 ofG. B. Feild, filed Aug. 3, I970 concurrently herewith (common assignee). This beater bar may be useful where each beater bar is of the same construction or where one of the beater bars has smooth edges thereon. In the latter case the beater bar 18 must have the same number of edges pitched in one direction as in the opposite direction. The beater bar 18 effects not only increased fibrillation efficiency but also prevents the film from riding off one end of the beater bar.

Depending upon the desired characteristics offibrillation, it may be desired to utilize edges which have various teeth spacing, for instance, as shown in FIG. 5, the edges 104, 108, and 112 may have 40 teeth to the inch and the edges 102, 106, and 110, 30 teeth to the inch. Those elements similar to the embodiment of FIG. 1 are designated with the same reference numeral only with an a affixed thereto.

Any of the beater bar constructions described can be utilized for fibrillating nonstriated film. The only change would be that the serrated teeth would have sharp tips rather than rounded tips.

What I claim and desire to protect by Letters Patent is:

1. A rotatable beater bar for a fibrillating film system, said bar comprising: a plurality of circumferentially equally spaced serrated edges, each of said edges extending in an axial direction of said bar and being disposed generally parallel to the axis of said bar, at least one of said edges being dissimilar to an adjacent edge.

2. The structure as recited in claim ll wherein the pitch of the serrations of said at least one edge is in the opposite direction to the pitch of the serrations of'said adjacent edge.

3. The structure as recited in claim 1 wherein the serration spacing on said at least one edge is dissimilar to the serration spacing on said adjacent edge.

4. The structure as recited in claim 1 wherein the pitch of the serrations are in opposite directions on alternating edges.

5. The structure as recited in claim 1 wherein the serration spacing varies on alternating edges. 

1. A rotatable beater bar for a fibrillating film system, said bar comprising: a plurality of circumferentially equally spaced serrated edges, each of said edges extending in an axial direction of said bar and being disposed generally parallel to the axis of said bar, at least one of said edges being dissimilar to an adjacent edge.
 2. The structure as recited in claim 1 wherein the pitch of the serrations of said at least one edge is in the opposite direction to the pitch of the serrations of said adjacent edge.
 3. The structure as recited in claim 1 wherein the serration spacing on said at least one edge is dissimilar to the serration spacing on said adjacent edge.
 4. The structure as recited in claim 1 wherein the pitch of the serrations are in opposite directions on alternating edges.
 5. The structure as recited in claim 1 wherein the serration spacing varies on alternating edges. 